SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '2bafaf81db406b2d0c42a938a6c4755592a5b2a59376dc20de247de3096a201f' 
  AND token = 'khsny6wH3UiPp1hU6VyMAu1y6iekqcXR8Dhp5VBsIfE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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