SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '88ff646fe4c6f228bd5da240f7a18280c17085d58b0c531b2c27c66c973aa271' 
  AND token = 'IFmpO6RYmUFO54Nre9Ngq7WluSnVWU/NIg+GwkCzOQU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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