SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '31b14f9959d5c542a02cadcb1310427cdc221335c9a9a726e807069dc41272e5' 
  AND token = 'EmL7AaHn6m2gzLVM1WBhGoJlct4J3tGRfQPxrSo1S74=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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