SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7c6e3dd8822e18ac5f239c52b9a2a4a8e5882fe7153431ed461571457354f438' 
  AND token = 'VHEq8aObXQsWQLGjuc/sKXE/qDpx3igHHUZL0NjGmFE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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