SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '21760181f1498068e3c5a71da4b4e50bb3a63244e837c547b3363f16156df1d5' 
  AND token = 'mINgFuFLcprqfumpqXRgJXYMOmbkj5R5IePGIiUKVHU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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