SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '59c04b679a3418693546d5e252cfa326f36de6d6579bc8994bcc3a3d01377464' 
  AND token = '8dtYOXKWHGKvBCWEqS3RvAioD8T0WlexnbD9WYhCuyU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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