SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bbcb99f345ec6a1831210b330711b5c0820840f0754051c05d3257b2defe50a9' 
  AND token = 'RtHP/KdFlSKYhC2hwMMo+cZdhD2Imymh6b0JxY56EhI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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