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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c81df17c3ebc1829b3ec0f05d4bb3df81225806a5ab71f831e3feaa8da53c8ac' 
  AND token = 'DuJ+MwX888Wv0gqGwPBDkk9KtKRhWKkeqO9iIFpRHNo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}