SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f53bd92ccde17be0c994c775673957bbb7e7b9787cf2eb71cc97a2e7d4473d61' 
  AND token = '1yAIiplgy5ue0fflYNsIV3lBzKcBMttRaI6nKOvbaKs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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