SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fb630e38c7f09765a51c9957f2a57106280f036cd81826acc0d7b5d5fc90d807' 
  AND token = 'u8HUAHFZbub0UNvcx30zXSv42WUN8ABaiNFxms3Ync4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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