SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c973fa324789d7f89140bd99fdbfd80e26535ac73596674af72eaaf1182f7d44' 
  AND token = 'bNtJrJggjN/No4EQqBs3XZG+M2dSP+79VXqHJbqyvMg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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