SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f87a11644e3857d9bae6e581697cacf7e9046891b055a7c6fca1cc3d0b56027' 
  AND token = 'hJCv8qGrBjvayFgQQfmm2klrY7RA607owuAIMmlvLZM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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