SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'a1de7a4459641381d4a3c7e75e585c0167ea0b4429ca925079cb849d849eedfb' 
  AND token = 'bmh516IBjq1KrJSHa9orEijMaU2LFfeYV+T5fq5UxB8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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