SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '6fc5b9091b52587f727d225ef6cd17f1897d60afda21b1536e92396f15935f32' 
  AND token = 'S/NQNhwblLsgD9hYJYJsuQKzsuoOik70OHbJXZlwluY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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