SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7a6905f9772076853681a837864535bf0ce504c9cd822cf8b5dc3a3a93c52853' 
  AND token = 'USYz5ocIoZWTZvr+i/Ju3U5QMaFpSPRUUdPHCcMJxq4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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