SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'e774c761cb7966e86c095f86dab4155975ff80a59fb36e38b899499f98fadab8' 
  AND token = 'P/0Se9Z53U7Oektjkn4P7fMy7i7dNkPd1J5/SevY3dg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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