SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '8a7dafae943d37fec433501fc84cec5410889ef5a12a38314d74e59362cbcba3' 
  AND token = 'HvUJP1RweYQNvcrSauKjmvYn+XbL/XahlBK7zGT/aMg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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