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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e78b5ca576af3a4a7ad5ade32a05349dc2d89a9d8a7b00ad1288ceba3af32f68' 
  AND token = 'OELw3RW/3oLjQgtd4Tmz4NEUP+DcH2yllbK3NjLLSSU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}