SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'c720f5069625f9202948f5b734312c4541bc723862a712e6ea1cbe1bb251dc07' 
  AND token = 'LiKBEWKAck/0RNxxvTrRSdJxBxIYPWGmeNzdHFIziM0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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