SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3b6630ddf46971e4430eed98033d9a9630f01f0f755345733f13a1c330475a3' 
  AND token = 'mGCVwgCqxmxabUBmZQC8y+f+6ybG9REsTkfWKVTizBw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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