SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '68d863f18972265a65f6e820019844f23c3550d03464e28f6174def6781c706f' 
  AND token = 'fpPpJ1Px5jpoBmwoozGbXE4AuDqUiPm3a3T+gUsjNY0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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