SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'b906f3d20a33586e81af102849ef286efe8266bc438446da27068638436e1060' 
  AND token = 'AWmCqJ7a4SsoCepvCBpO6prXz9QF5d7SbFNvPLBj9pE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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