SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0621e634174a3970a3e88fe98a854f8bc78e7e71aab72bfa21b7f6aaff9a6b39' 
  AND token = 'ZU7+F+s6dYi0DfRtDrtEIhlU8YrxlGLb28qzAZWJCjA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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