SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '98791958402815028e8ad0a92042ccf8e2619f24623b1e46323c8c9a0054cea3' 
  AND token = 'Kq0smaV0wQ/Jn7x9aPV7UbbOS/kVuoK+S17PumSRrcc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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