SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9e43105f224a52ac559743fb1ba76350c732228af8b25bb3d8eed01278d38e9' 
  AND token = 'tHoCRMSW7aIrbTFodeIrpKeTX39u3/BQ3vBm+P0tCo4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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