SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4ea0ea87cd474375076b40938208dd30faafbf9c74c3bd4cdf83f2389c6175a5' 
  AND token = 'DBHs+aKiEb1xwx6jEIwnKwbxTUUuUBf5u2j0o6sEUGI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00053

JSON explain

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