SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8c1e103e7f2b30ff8c7fd48a230976409dd6cadd5eb328cab22d837439334e66' 
  AND token = 'SMMbNn2N5UpGakb81AuhiqT0NIxGnsS5WhAMpImMGoM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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