SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fe40823debe434cc40cc6b2eec582a3c26fb69b4a96426a99f3141e9980578b7' 
  AND token = 'LOyqEz0rn4yjnZcg0OBBlkfPAPvJVyBiirzgZ4UWv0w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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