SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '974f10d50dc2d21665b1f1c6cc25252f8a8ac111b9a53a74a55804d81297a04c' 
  AND token = 'flgidZpGmKzcq1KGW7+LCpbr3Bu0jHs7XH7u7pz+kWw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00055

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}