SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '66ce4b03c752847a5f236080962aa9e489e272578bdbe3ef2b27c06c28815568' 
  AND token = 'Via56pnkXdoyXDzxtKHCLWk1q2/UXNhphpQI/muLtUU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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