SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '0391906819ad994471de86ef7c5a1c25088b31cee4009329aa3f5de21cb3c855' 
  AND token = 'cytTfY/XghTbpnRB4BWmEAERCH+OXIf2leqeB7bGGiQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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