SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f853ed53650d1ea3814ded77134dd2e0bcb8cb3fd72da51f290ddd460fe4f24e' 
  AND token = 'UdDHJnssr1vMChLdYqZ1G6P8eOyeCRmMsCHE44RQDcg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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