SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '52806981ca6e9a61afbbb2783920aa35eeb617b459624c1fb46426467440fddd' 
  AND token = 'VSNgHCguoYVPfG9HYDDHIcxTUQpicFk2pwRoQjsn2E4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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