SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b1f5982a4a4dd392399cbbecb332a042252403c8448339daaba3ab10f6fcfe5c' 
  AND token = 'aboc3Z7xhJSWYwH+C/jldtAOrdmjO3oDVbAbHIjzULg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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