SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b10902da5578e6e11cb740653ebac59480370c11196a05cf02fba206789c1ff' 
  AND token = 'ZX8hKuWU2fe1BWgcxqbnUz1l+CDjBJ/C3JK17lnfXQQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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