SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '684fc3d7ae3b47e1f897a9d58681efcc4eaa3b64a254b835bbc2fdb391d3c56f' 
  AND token = 'NZ8nLOVTqoka/TKL5yg1+NQqE3PN13/zqJojJFnWKj0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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