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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a3b664a0f0f0494f79eb502806a811ddb4cc7a10bd6a79d5b69bf97d41f01aa5' 
  AND token = 'XReB9vqX9AhzFn/u/wFC1kI8+u5lyAsSjYpBtCE0URM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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