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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '67d33765aa38a648268f9ecaeabe45e76f0ecd55014df619520e59c471e5a619' 
  AND token = '7jT38MYyGzHs/wP4AF0mjr8aFDI/56+PyYkvR3SLnB4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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