SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '381cc2324bd42227b810a18e305e980578987125b2b4739e59d02e67a477de4f' 
  AND token = '5TkhJjIgNNG4wXx/CZ0fYIq9IX/6PjHkzc4TqjdEKG4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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