SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e2f5acc5fb0ee3a8752f74995683cd4285729bfb21b5e44cc3cc5ab198929ab9' 
  AND token = 'UJWKDu9MRgA/HCySX76Hi9wp/SCmUJ1xOsNjxhvA+SI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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