SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'efbd7a9dd1f13a2f93d2f9d8f51b8b236058c11b98d1a9e77eeca904bf80a14c' 
  AND token = 'xLOV0VBlhai3jv3y4wPjw87+LwTFg+rqm4X6JTmIshg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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