SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0474fd830b5b1221e22a4b4845cf30f8461241df9b25dd9ddd9559211e90aea9' 
  AND token = '8brG44AkefJUu0w6pywRfX8S76FjzD61rIIAF2ZW7mA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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