SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bd4419eb9438245a3374cc0fba93fc811ee597f2d20b428f74d637445eae43a4' 
  AND token = 'eJqbz0MDJQyKSfLr40XnD67/hYwHuwngGPS0Xujws7A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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