SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5816dc03f5303e9b1e2f6940c58e3945081157640754b7f4e71b461733313dae' 
  AND token = 'rx0aw6AgLhOOvdzCxHjqELBDP6lvQwYNQ7a2gFVpjYk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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