SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '98971e5fca7069f8dc725e3a6531b920896697f5f07cb33d0f45342ecc7fc889' 
  AND token = 'jFyGyNiZRENMsGELSzaA/7n1uK9/JHM4Z6gUApNiIC8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}