SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '5af715b8143137f07add62654d8d346470298a26ae881d703ef6a6379c69d3b5' 
  AND token = 'zQD/YjYN9FRTXzIXsEMnfClLLtkBMevyJfNaveJq3bY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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