SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9b522fabca2da6852daea5ddb48a7aeece0089307a8f44c3f240486092c287a4' 
  AND token = 'DOxfAdqnsGjccucyGXeOu1ir4G4u0YukiBvbndlHCew=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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