SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'befa43a3f37861f64f18312daf4b34de4f6b89ddca3bd790ba8e8cb0387f691f' 
  AND token = 'UESuikUPMWGzQOpxmheHOlzaGFHa50FPa876R+19MEQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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