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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e55b9ad2cdb357670e1dbcc1abc73d6d087ab949085caba2c4af3d1cf2aa36ec' 
  AND token = 'uN7H8t1VExLGjgXZOQpUnshJA1MDsxfybW2Xw6YQzC0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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