SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5648bc90d84c8adcabfe9aac8039ab2e54c20708be3b419d3023e3d8646bd9fc' 
  AND token = '6u3WyeyoQrvLag72+dXp0OylLordIQcWLOW994AMYEs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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