SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '820b3b7988289d8eb8dccc663f7e3a5ba099206cf7df96dff88dcb285450d6f6' 
  AND token = 'l3yjnzEhBzpTcAHHWwzz3ot/LcvGLQN3ZZVHtjkepIE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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