SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '981935ff836609211c40cf9e3f3596208be5f7afb58beffe07bb6c9915075f81' 
  AND token = 'Rfpk9M++UGIYc0M/OjvSLsUfoUmV+lWLu4wLk4QihhM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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