SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c8d27a0fe74764cb8cb34a37581f4d67b315d53d2e674eb4f730f4049d919b56' 
  AND token = 'qPLm4KzwIo/HnQxzgVFblGd+jwIVACj62KVM1uLUsiI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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