SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '752775a76f4d0748cac5a96681b3af3e7ac57e550c5afc2425f911de0fa1c392' 
  AND token = 'gzc/yLM68oQC9ilTbqqY6LOfzmgMzdbB27LUFTgB4gc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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