SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '54f0af92f4b713d32997c20da76962f45c928e087ad9f618a3d25484694a7940' 
  AND token = '1O3d+kqXm5zJsjOItIxrhecuhjwagHOg36t9MakX3PA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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