SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9be6c7646855c4d979ed547fcb9abdde6bfa67685e24f0bf0e51fd4f45f0aa50' 
  AND token = 'ImPY1f+T2FBpZh+N435GntbUHg2JW6llnPgqJjLlO/g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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