SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '31dd98b9016b9dc253e8f41cc729e526011383564c103866d1f299656ded3c7a' 
  AND token = '4e4JDVs9IsjUrAX4ITwg9xsmsCmzcFcELaQipmO6nAk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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