SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7b8fe4b58e0788b859b899b0164cb875501efd4b496501272bbf04d437c05aa1' 
  AND token = 'J2vxugxoiHMDTFxcu1EbBIzrcwAgGIPfj6yzU9sW/cI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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