SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1c5195d778e5c54028f2f0a281eb7646b24be36ff1cc2de94b67dba5d0e5bc9c' 
  AND token = 'mDEvLtAbrXIxBUo2R4hDXvG4lbkHNb2Pg7nwPsZyCZY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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