SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '19ead4a3c06912644b4ce63f47d59cb92261a5729b49646536c75a116a29ffeb' 
  AND token = '8sHBvumkE5BnQWydAabrMPZvnO6Lfuk7BaITOnXACIc=' 
  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"
    }
  }
}