SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bf877d18916d31efaa13616f7116de27e85b2ebf6feb9f1c12987984a6eca84c' 
  AND token = 'bOwQB4/JxjwJTOdxzQZqUZv6ietl4Ul/XPGgDr4zM7w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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