SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a40c2df0c558671330d08eaa09ecbd66ff810b844d251ba3b3461bb64c2d1255' 
  AND token = 'bN59bsO4Pqg+lEjxcLN9Y1uoToaMfmRcvr73Jv3TSfE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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