SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'b3d044850097f2c9812fc66b1b944cc1d0d2eb27f12e98ee344dd34730e2860a' 
  AND token = 'FJNdVVagXvzY/wOhxOlYv8Ffc3AFSoGPoyt1dM5D2g4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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