SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9dc39f6c3ae9efb412431f58135e1cea087ffb6d72e03815090d6ac7c8158255' 
  AND token = 'W9BkwgmOD0Z9LtznqplDYqpusBkBOAQIjxeD4cT9i4w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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