SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '70bb1e351ae58c43dfe68c25121a323e2a225145ae87d6a40185efbd269f5487' 
  AND token = 'lb4AEmY1ahqwggKXqMaQSJfp6vlUBgGH8WksU8/MCQQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}