SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b5aaf458ea0e0e144578203c959309bfc442d3ece819c0b84bd9801513549a40' 
  AND token = 'oceZUiefmO7ZmcZHDuzNydAlajRWjy7zWCAcQ4d5RGo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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