SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '88d5186342477a7b735473b94a475403862d2d6fd30959ec2222de7502369b41' 
  AND token = 'iyI0/hfnMC7BaY+A0bR3LHGXpSGe+yqgPqqh5rGlb7s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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