SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '779de7ea66c1d03dbe1462c39622635780a03b496da743b35282f0e7ca4abea7' 
  AND token = '93e/AfGkhHJDJsLxOU4W4KRnG5zGr326Q5XOJTrGrB8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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