SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'db474a5482a3ea30f65c5936df7327a859201cf42d9c673936bf4607a1a6c0d7' 
  AND token = '7fAZYu4mZtAPgwJiRvC46B+2HfUDCW4GYRcEjtuLp9Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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