SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '03ef2a3036dcbd929036c835280a5d9032eaa42fb9729603f56e1475fa132608' 
  AND token = '/x+JwZydqrccknxKwUv175Ho1uos5nBj/P0Nxozokj4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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