SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'ad6c40457efb8e59ff8f97180680e644330ea8d0fa9bfde9daaa233648139b15' 
  AND token = 'EEl20B562XghESPqjsQvvxfFjgwOQJveUXSSkqVWG0A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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