SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c227b763651401035ae3c67a942346d3e4aec4400bc8d16c12390af571f049b7' 
  AND token = '6dAs1JFBVXPc4QYS4otBgsUCGlgpGgg4d+CYm61hL+w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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