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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '99462c2e521def2b2345210ab5a395e2656c53d261c4499398a3ead4b80e8c43' 
  AND token = 'MHsJmxtk5e+MZO8DfLQKQSO3hsZy6URt6lhLIIe1Qig=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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