SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ac5cdbbab8c63386eabe7d4ff51377165e2dc4aa48cf8159e54033da6adb2fde' 
  AND token = 'hygfh5Bv6RI+7zLpu0P8GWkDNaltDzcDFRDiNKBHVEA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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