SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c5a7911dbe503c8db8d93ea1ff95b2652c3046edca91eae37eea9441438dd8d3' 
  AND token = 'O8tQiXLQeDi2bHOfbeAfaQkXJOu2ZM8xkzc8xXR3Ecc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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