SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '846307bd7af4ef6801f8416a1f062faefe1ba42dbd8c700dc17f5f7aa94d6f5e' 
  AND token = 'KqTRj/+AhaffpJyCanD4RS3hOfJqJtBIaGUEEcw4DIk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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