SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '6e97287d0152319064e2c2b3717fc3c2f0f2b4142d8d138cbbbaf5cf64c138bc' 
  AND token = '0TUu2efRCMzx6tqKnAN49O45QLN3gjiEkH3hm5MtW9E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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