SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4a75a2614c5184ae7d80afd400249439a54a46bbd24836f35b1662b84388379c' 
  AND token = 'MHWqBA3VdUjyFUbCfCfhA1lCRKeWUOt+YknffIH0Yd0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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