SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4624b4020a3fc582fbe20123a51989cc0d039aa38847ab4fc064e0e89809b082' 
  AND token = 'vS9ghz6hIattZkrpoNUD3WHq74z6JpCck9xUWKE6CCA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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