SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f943d753bf817235eb037befc28c3603fd4a4231792ddff48c3afabd87e1cd82' 
  AND token = 'pLrhyc3oa3cPlwuZM1KCnBCFwPYNZUgElbRG7+IQE1s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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