SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fd8114cb2ff6581549cead61adc7ff8d52f7a53dc5eb366655d1e88c41432b88' 
  AND token = '6ijZfnkC9oBpxXH1940hbKqhlVUQ/Z/CsA5bStY4KHI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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