SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '45ece33a1cccea736e49ce52c0340ec8254b8289f95d197ec33c7fb82c254ea9' 
  AND token = '5mdNMbkVkbYIf9AiSm+k9M8Wv4m+Cqquw1Z4EwI9VgI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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