SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8d8b85cfffcb22309b42ba64e912096fac848aa42d824475187e60a950a127c3' 
  AND token = 'Uf3kyNdyVXYSTCMhghLDb421eTvAhi+ST4OrgJP6EUg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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