SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '29042d61855a0d9006d51c34654c1cfacea49915036407e23cead5ede0266b9f' 
  AND token = 'dLCLwjAqr/90GdPQW4JFYL2bwZqBz4KHVljV+9U65+E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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