SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b8d90631047e29467161daf51f2de65582923e4f37df8e5066b733521374b90' 
  AND token = 'zfZX9PjXo0CJoOiv6KleDMw5SF+Jh6n37yfJquztTJQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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