SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75c9397057d6a1df90829da7343970de42bd9bae5600329ea3d62f75bb667356' 
  AND token = 'XFZltSxN+3vehjsjM0zhJADgb7goAHqXeuxfu9pUH0E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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