SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fc4452baf55c0bd806a851eae618258afbb09c488335b54e845cfc4e7f4612fd' 
  AND token = '0aCc4cX39ANoGzRUFdMwWUIlSnEOZLLd79vAh3iZQvo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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