SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76b588f626df614e8cff517741985b5112df7330d44b540903d6b5212943eaba' 
  AND token = '3QCn5FLT/C5BS2+2l1WFHK/NzJJLMli7bJvflsN0Jcg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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