SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1b736831e0e213c786f99c4da2cd982fdbf49bae2bc6d1a0d165d6d4b4a55848' 
  AND token = 'H/qrH9viBMSFC81/V1LlYureHnN9cAOby/GJqUAYasg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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