SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b02ebbc32e65231cc79032d1000587a1948fe98cf80994ad96e77a2fd518475b' 
  AND token = 'z8UoYQh9LdKje578xa8htN6wFZaEkUEABa3jPDIrJ6E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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