SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a239dcbbc282baf3320fa8c4f37a83d17334a9a1588895d257d191654c854b34' 
  AND token = 'hpVw+5CUEOgEv6TzLCQs0qU9spAvxMybg0mlKltMWCg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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