SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42f62b2a17b423474f45efcd4e1e11064992064773b2d77a847398c620e2cdf8' 
  AND token = 'EwTS9SNN8atVFs3N/YFl75smKMlcPI1s5feyu2xPniQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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