SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '36892e6ef631359aa514db0da94b4487467e0f6a3d0cbba2972eee7ac4c2f10f' 
  AND token = 'Mv03WvEoN1yGSzLdHOzUi2C7JObCYNl7+BKR5hp4OPI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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