SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '19badf94d45725448f301d4624946e05ab4558d876938e67a902ca62f33ae109' 
  AND token = 'n9ZqRdRSGElLj+lYsDMSDfVeTKSV8ff9EoqQMyjHs0s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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