SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2efe3d10920937693ed983d3798b13e051fd860b7bf20f98d40404fec5669b03' 
  AND token = 'VcMpIxl0X3XL9ZSpOPIc5nRmhKgyjqUOga8tNFrr0Yg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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