SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '38bcb1b6d64cd137dec5eed37a8516104ef2a85797ae0c4c9ab986ee3d571fc1' 
  AND token = 'tow/ETx6CVJ4epd1MdSGPc3NJrsbQEUm6EpI+MeNTg8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}