SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dcdd4fa15924cd8be942a1c146d93e2b37ce284904f70db076982b3a57c0a2af' 
  AND token = 'rYP4y5CDRjZkjso1pV2A0KsGv/1KUPRkR7IX5mGWW8E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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