SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'dd12d96389e44510c3a633945ecef501331d60f4c973dfef5730b4c6c1fbeb62' 
  AND token = 'd7f7lMVjnPTX9sddrhO0IgDmS3QJesKJJckL5+3fZDY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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