SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f87895603e5e0b683d30b16e415cc7f9270ee2b0a816d290da11589290893d54' 
  AND token = 'i5ScmbZxaWP7uChwscfiuVMvGYexAM7GuZzXVrfbWpw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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