SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1f0aeb39a0a41de38487d74765d83551c3289fb65d42bc8ffb45b0a964243c77' 
  AND token = 'vlT9oKsBODCvDDBF54h2s6PNiggyroCzdwtZhGWacyY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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