SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e4f4c1e890f03c0ce83704e5531a5b0423ef4c53ab9d1ca4d7d310759456f428' 
  AND token = 'xUnFVWCNEhgobDDQzq9LBAIynvGmCGHltMGZRItT7NY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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