SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd29cfdbd513ef3670315a10a17a6c0e0c7be4625f76ed3eb70e0f7a28e4ce770' 
  AND token = 'imZIG5DjCydsq1s2iEwmgltAnMYRjYtJwwbEaRLUHWI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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