SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '0a935468cee08d3dcff9f53fbb980a8a76a4e3b954885fb36392d4566f40a941' 
  AND token = 'mqZWje4GOIEpkRylembrydBOTjAxuTwGhqQcQxqLGpY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

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