SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '976cb1a2c4533d306ec9945256c496e73f2874631a4b36c411a860fe1323d185' 
  AND token = 'bfMSkNp5g8tzhxv7LDHTINz9MwteYXKaOzTHjGyehIg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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