SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '31c3f775652a7049ce47463081e7edf6e4394461dfd6e70f86a06f259dcd9cd8' 
  AND token = 'SAlD60v0GbX+I6erWJPNWZVL00+Clvhs+2sOPzMxiWQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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